Patent GB-1315556-A (GB)
Title: Process and apparatus for production of profiled rotary tools
IPC: B24B53/085
Filed: 1970-07-31
Abstract: 1315556 Grinding; trueing grinding wheels; milling screw threads HERBERT LINDNER GmbH 31 July 1970 [1 Aug 1969] 37197/70 Headings B3D and B3K A process for production of a profiled rotary tool, such as a grinding wheel or milling cutter, for generation of cycloidal thread flanks 2, 3, Fig. 1, on a workpiece 1, comprises displacing a dressing tool along a helix line 5<SP>1</SP>, Figs. 3 and 4, used as a generatrix which coincides with the helix line on the addendum circle 6<SP>1</SP> of an imaginary mating thread 1<SP>1</SP> engaging in a thread 1 to be produced, the spacing between the axes 4, 4<SP>1</SP> of the imaginary thread and workpiece thread being equal to the sum of the root circle radius r f  of the thread to be produced and the addendum circle radius r c  of the imaginary mating thread. The flanks in both the imaginary thread and the workpiece thread may be concave (Fig. 2, not shown) or one thread may have convex flanks engaging concave flanks of the other. As described, the rotary tool is a grinding wheel and the apparatus for producing the profile on the wheel, three dressing tools are used, one of which moves along the part a, b, Fig. 4, of the helix path to dress one flank 9 of the wheel, the second tool moves along a path b, c to dress the edge of the wheel, and the third tool moves along the part c, d of the helix to dress the other flank 10 of the wheel. In the apparatus for carrying out the process, the workpiece 1, Fig. 9, is mounted between a headstock 14 and tailstock on a saddle 13 movable along guideways 17 on a frame 12 by a lead screw 16 and nut 16a, the screw being coupled to a spindle 18 for rotating the workpiece. The grinding wheel 7, inclined at the helix angle, is mounted in a pedestal 22 movable towards and away from the workpiece by a screw 23. The screw is coupled to a further screw 29 of a dressing tool feed slide 30 on which is a dressing saddle 36, Fig. 6, movable parallel to the workpiece axis by a screw 39 and nut 38 and a piston-and-cylinder device 47, 48, the nut 38 being disposed in a slide 37 movable between adjustable stops 51, 52, and the screw 39 being coupled to a drive in a casing 43 carrying a motor 44 for rotating a rocking shaft 46 coupled to a dressing device 61. The dressing device consists of a beam 63, Fig. 7, having two branches 64, 65 slidably adjustable to positions determined by stops 68, 69 in guides 66, 67, guide 66 being secured to the rocking shaft 46 and guide 67 to a pin 73 in a bearing 72 on the slide 36. A control disc 83 is mounted on the shaft 46 and has limit switches for controlling the rocking motion of the shaft. The beam 63 carries the two dressing tools 80, 81 for dressing the flanks of the grinding wheel and the third tool 82 for dressing the periphery. In operation and with the slide 37 against one of the stops, the slide 36 is moved by rotation of the screw 39 at the same time as the dressing device 61 is rocked so that one of the dressing tools moves along the part a, b, Fig. 4, of the helix to dress one flank. The device 47, 48 is then operated to move the slides 36, 37 so that the tool 82 moves along the path b, c to dress the edge of the wheel, the device 61 being held in the midposition of its rocking movement by an index pin 89, Fig. 7, engaging a hole in the control disc 83, after which the screw 39 is again rotated so that the remaining tool moves along the part c, d of the helix to dress the outer flank of the wheel. In another embodiment, the workpiece is removed and the dressing device mounted on the carriage 13 at the front of the machine.